Air cooled internal combustion engine



July 13, 1965 J. LECHTENBERG ETAL 3,194,224

AIR COOLED INTERNAL COMBUSTION ENGINE Original Filed June 27, 1962 3 Sheets-Sheet 1 35 I/IIIHHHE Influx @MMW .51 0 12mm; Iafiarzfiflaizarsan 55171? HIM/31 2255512 y 13, 1965 L. J. LECHTENBERG ETAL 3,194,224

. AIR COOLED INTERNAL COMBUSTION ENGINE Original Filed June 27, 1962 3 Sheets-Sheet 2 July 13, 1965 L. J. LECHTENBERG ETAL 3,

AIR GOOLED INTERNAL COMBUSTION ENGINE Original Filed June 27, 1962 3 Sheets-Sheet 3 United States Patent 3,194,224 AIR COOLED INTERNAL CGMBUSTION ENGINE Leo J. Leclitenberg, Elm Grove, Robert K. Catterson, Brookfield, and Joseph V. Reichenbach, Milwaukee, Wis., assignors to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Original application June 27, 1962, Ser. No. 205,658, now Patent No. 3,118,433, dated Jan. 21, 1964. Divided and this application Oct. 3, 1963, Ser. No. 313,546

(Ilairns. (Cl. 123-119) This invention, like that of the application of Leo J. Lechtenberg, Serial No; 205,658, now Patent No. 3,118,433, of which this is a division, relates to internal combustion engines and refers more particularly to single cylinder air-cooled engines of the type widely used on power lawn mowers.

The object of this invention is to provide a simplified and more practical carburetor for engines of the type indicated, particularly from the standpoint of assuring continued freedom of adjustment of its throttle valve and choke valve, even in dusty and sandy surroundings.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention, constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a vertical sectional view through an engine equipped with the carburetor of this invention;

FIGURE 2 is a separated perspective view of the carburetor, a portion of the fuel tank on which it is mounted, and the air cleaner;

FIGURE 3 is a perspective view of the assembled carburetor, but with the air cleaner omitted;

FIGURE 4 is a fragmentary perspective view illustrating a detail of the ignition grounding switch of the engine, with the various parts shown separated fromone another; and

FIGURE 5 is a top view of the carburetor and adjacent structure, but with the air cleaner removed.

Referring now particularly to the accompanying drawings, the numeral 5 indicates generally the main body of the engine which preferably is a die casting such as that of the Lechtenberg Patent No. 2,693,789. Hence, the main body casting forms all but one of the walls of the crankcase and also the finned cylinder 6. The open side of the crankcase, in the vertical shaft engine shown in FIG- URE l, is closed by a cover casting 7 which has the mounting flange 8 of the engine formed thereon and which also provides an oil sump for the crankcase and contains the lower crankshaft bearing (not shown). This lower bearing and another upper bearing also not shown, in the top wall of the crankcase, rotatably mount the crankshaft 9 of the engine, one end portion of which projects downwardly beyond the mounting flange to have the cutter blade of a mower or other instrumentality to be driven secured thereto.

The outer end of the cylinder 6 is, of course, closed by a cylinder head (not shown) which is secured in place by bolts or capscrews 10. As is customary, both the cylinder and the cylinder head have heat dissipating fins thereon.

The upper end of the crankshaft has a flywheel 11 fixed thereto which also serves as the rotor of the engine magneto, indicated generally by the numeral 12. Air

propelling blades 13 on the upper face of the flywheel provide an air impeller or blower capable of delivering a substantial flow of cooling air for the engine. Duct means indicated generally by the numeral 14 directs the cooling air transversely across the finned cylinder 6 and cylinder head.

A rewind-type rope starter indicated generally by the numeral 15 is mounted on the shroud and connected in the customary manner with the upper end of the crankshaft to provide means for starting the engine.

The engine is of the L-head type and, hence, has intake and exhaust ports 16 and 17 in its cylinder casting. These ports are spaced apart lengthwise of the crankshaft axis with the intake port 16 nearest the air impeller or blower. As is customary, the ports open to valve seats 18 and 19 in the top or outer face of the cylinder casting, and with which the intake valves 20 and 21 coact in the customary manner.

It is significant to note that the intake port 16 opens toward that side of the cylinder which faces the impeller or blower, i.e. upwardly in the case of the vertical shaft engine shown in FIGURE 1; and that the exhaust port 17 opens laterally or horizontally away from the cylinder.

A muffler 22 is bolted to the cylinder casting over the mouth of the exhaust port 17. This muffler is of novel construction and forms the subject matter of a copending application, Serial No. 233,005, filed October 25, 1962.

At the side of the cylinder opposite that at which the intake and exhaust ports'are located, is a fuel tank 23 and the improved carburetor of this invention, indicated generally by the numeral 24. The fuel tank 23 has a generally oblong or rectangular shape and is mounted directly alongside the cylinder crankcase casting with its top wall 25 substantially in line with the upper side of the cylinderor, more specifically, the cooling fins on the cylinder, as clearly seen in FIGURE 1.

The tank 23 is secured in position by means of suitable mounting brackets, spot welded to the opposite ends of the tank, and bolted to the crankcase cylinder casting.

Since the mounting brackets are spot welded to the opposite ends of the fuel tank, the points of securement of the tank to the engine are relatively Widely spaced, and

being as firmly anchored as they are, it follows that there is no likelihood whatsoever that the fuel tank will work loose as a result of engine vibration. Also, since the carburetor 24 is mounted upon the top wall 25 of the fuel tank by means of a relatively large flange 26, the bottom face of which seats squarely upon the top wall 25 of the tank, utmost assurance is had against loosening of the carburetor. The flange 26 may be secured to the top wall of the tank in any suitable way, as by cap screws 27.

The carburetor is of the type disclosed in the Brown et val. Patent No. 2,529,242. Hence, it has a die cast tubular body 28 which provides a mixture passage 29 in which the fuel and air is admixed and from which the fuel-air mixture issues for delivery to the intake port, and has the flange 26 formed integrally therewith. The fuel is drawn into the mixture passage 29 by engine suction through .a'suction tube 36 which projects per-pendicularly from the bottom of the carburetor mounting flange 26 into a cup or reservoir 31in the upper portion of the fuel tank. The fuel delivered by the suction tube 3% enters the mixture passage of the carburetor through jets (not shown) under the control of a needle valve 32 in the customary manner.

The cup or reservoir is kept filled with fuel from the fuel tank by an engine-suction actuated diaphragm pump 33, which is mounted on the side of a carburetor body opposite its needle valve, and the inlet of which has a suction feed tube 34 connected thereto to project down [into the fuel' tank with its suction 'mouthrlocated near 7 the bottom of the tank.

, 59 which is pivoted, vasxat 6t tothe topface of a mount Air enters the carburetor through an airscleaner 35 Whichpreferably isof the type disclosed in. Patent No. r

2,999,562, and which is seated uponan upwardly facing;

flange 36' encircling the mouth of an air inlet port 37,

being removably held in place by a screw 38which extends axially down' into the air inlet port and isthreaded :ihto'the bottom wallof the carburetor body.

. Theair'cleaner 35 not only serves to clean the air' fed to. the carburetor, but also provide filtered combreather '39'which-is preferably-of the type shown in Patent No. 2,693,791, and hence, is located on the side;

of the crankcase adjacent to the-intake and exhaust ports. A tube 40 connects the crankcase breather with the air intake port of the. carburetor, for which purpose the carburetor body has a tubular-projection thereofconnectible with the tube. r

The discharge end portion'42 of the mixture passage of the carburetor is connected with the intake port 16 by a tube 43 Whichex'tends transversely across the up- 41 at one side 'rnunication between the. atmosphere and a-crankcase" wardly facing side of the cylinder. One end of the tube 4 43 telescopes into the discharge end portion 42 of the mixture passage and its opposite end'is received in a die cast elbow 44,.which' is bolted to ,thetop'face of the crankcase cylinder casting over the port 16.

'ThIQ chokenvalvead of the carburetor and its mounting are rather unique. Both the choke valve'and its 7 mounting shaft 46 are molded of plastic such as Delrin.

The valve is a generally circular disc having a hole 47 at its center-of a size to permit the screw 38";which holds the air cleaner in place to pass therethrough. T0

enable the disc-to berotated by its mounting shaft 46 through 90 the disc is formed with oppositely facing semicylindrical grooves 48which embrace the screw 38 when the choke valve is in its full open position, and the, inner ends 49.0f these grooves, whichactually'provide the edges of the hole 47, are disposed at an angle of' substantially 45 to the plane of the disc, to abut. the

mouth of the intake sides of the screw when the disc is in-its fully closed position. Accordingly, the screw passing through the choke 'valve disc serves to define the angle through which the choke' valve may be turned. a

The mounting shaft 46 of the choke valve is journalled in a bore 50 extending radially through the cylindrical wall which defines the air inlet-port 37 and basal. bifurcatedinner end 'portion'51 projecting into the air inlet" port toembrace the adjacent portion.52 of the choke valve disc. The slot defined by'the bifurcations of the shaft is just wide enough .to snugly receive the disc portion 52, and'parallel ridges 53 on the opposite facesof the disc engage the :edges of the slot to holdthe disc against lateral edgewise displacement with respect to the mounting shaft. a

. Endwise separation of the? shaft and disc .is normally prevented by a detent consisting :of a pair of ridges 54 i on theopposite faces of this=discl and transverse grooves 55 in the sides of the slot defined by the bifurcations of the shaft... To effect assemb-lyof the choke valve and its shaft it is only'necessary toinsert the valve discinto'the engage the detent between the shaftand the disc;

7 air. inlet port, alignfits portion 52 ,with the bore 50 and insert the shaft 46, whereupon the inner bifurcated end portion of the shaft'is slid onto the disc far enough to A torsion spring 5 6 011 the outer projecting end per- 7 position. One end of this'spring is hooked ontoa portion "of thecarburetor bodyand its other end engages 'tion of the shaft 46 biases the choke valve to its open a lug 57 projecting from the shaft. An arm 58 also pro-1 'jecting from the outer end portion of the shaft.and

preferably disposed at a right. angle to the lug 57+ 7 .-provides means by which the shaft .may be rotated to' close the choke valve. This is done by a control'lever the carburetor. r 7 The .control: lever 59 has an arm 63 which'swings in 7.

ing plate l' which, in turn, is attached to the carburetor body preferably by means 'of screws dzjpassingthrough V clownwardly projecting flanges on 1 the Y mounting plate and screwed into bosses; on theside of the carburetor j g 61 i-s 'thus firmly attached tobody.. The mounting plate an arcuate path so disposed .with respect ,toithe location of the arm 58 on, the outer end of the choke valve asto collide therewith as the control lever is moved me clock-; Wisedirection, as-;vie'Wed;in FIGUREi 5 beyond its fullj line positionpthereshown 7 Another arm 641cm the control transmitted to the throttle 'valve of the 1;car,buretor ;.(not

shown) through alink 67 which connects with an arm 68- fixed' to the tthrottle -valve shaft. "The arm ofi has a portion thereof located tocollide with a fixed abutment 69 to thereby define the full open position of'thethrotrtle valv'e,; and ,carries ascrew .70 whichengages the other "sidej of the abutment 69 .to define theqclosed position of g p i the throttle ;valve, the iadjustability of theiscrewjtl iaffording an idling adjustmentfor theengine.v

V The contnollever-59also provides the means; for-closing an ignition shorting switch, I indicated generally J by 'The. manner in which, this switch is constructed and mounted onthe plate llis'rathernovel. As shown, the ignitiongrounding 'switfch '71'comprises' the; numeral 71.

1a bifurcated spring metalstamping; havinga short-arm 72 1'and a longer; arm 73;. This st-ampi-n'gis carried by 7 an insulated mountingpad 74'toqwh ich itis secure d by having its rear; edge "portion {75, which is; curved down wardly engaged swith raalfiidge.76 ;on the underside? of the mounting pad, in, coaction with' a vnovel. connection 4 between the short :arm- =72 of the stamping and a small boss 77 on;the'underside of t-he'mounting tpad. This boss projects througha hole'781in the short; arm 72 and a tongue 79fsnaps overaledge 180 on the boss. With 4 the stamping thusv attached to the pad 74, its1long arm-' V .73 lies flat against the undersidei ofthe padlwith a finger Y 81 on its extremity projecting :t'hrougha hole 32in the i mountin-g plate. to be engaged-fibyfa portion or; the con- Itrol leiver. 5'9 when the latter is moved to its St-op posi tion, thes resilience of thest-a-mping permitting the arm 7 7310 flex as the grounding connection Eismade;

the" padv and slightly beyond 'a hole 83 intherboss 77.

This provides a convenient :wa'ylof connecting a wire. lead 84-with. the metal stamping.. To d0 .SO, theshort 1 arm ,72 is ,pressedl'upwardly beyondkthe hole to allow the. baredend' of the :Wire to be inserted into the hole beneath "the arm 72', 2 which 3 upon being released makes secure contact with the wire. 7

Thei'nsulated mounting'pad 74 is attached to the plate.

61 in its proper position by means of a pair of upwardly,

directed spacedifingers "85-86 on the pad. which embrace the portion of the mounting} plate lyingbetween as'lot 87 therein andits adjacent edge. RidgesSS. on the :outeri ends fil n p over theedges'of theembraced POF-tiOD-87Q Q V and Stop "positions of the control lever;

The mounting plategso l. 'hasfysti ll' :another? a function.

When mounted on the: carburetorit preclu'desfseparation V ofethe shaft "46' from, the choke valve discs Forthis pur; i

lever 59 is connected. through a spring 65 with-a leven66 connected in' the cus tomary manner'with av mechanical governor,-'not shown, it being understood that the lever 66is21nov'ed back and. forth by the governornand that suchmotion thereof is The. short-arm '72 is:sprung .downwardlyawayfroni i 5 pose, a lug 90 projects from the mounting plate in line with the outer end of the shaft.

What is claimed as our invention is:

1. in a carburetor having a tubular body providing a mixture passage in which fuel and air are admixed, an air inlet port leading to said passage and defined by a cylindrical wall, and a choke valve to control the admission of air into the mixture passage through the air inlet port, the improvement which resides in the following features:

(A) the choke valve is of the butterfly type and comprises a disc of a size to substantially close the air inlet port (B) and the mounting for the choke valve comprises (1) a radial bore through one side of the cylindrical wall of the air inlet port (2) a shaft journ-alled in said bore having a bifurcated inner end portion projecting into the air inlet port and sliclably embracing the adjacent part of the disc,

(3) interengaging guide means on the disc and the bifurcated end portion of the shaft parallel with the shaft axis to hold the disc against the lateral edgewise displacement from the shaft, and

(4) interengaging detent means on the disc of the shaft to firmly though detach-ably hold the disc and shaft assembled.

2. The carburetor of claim 1, further characterized by the following additional features:

(A) the disc and its mounting shaft are plastic moldings, and

(B) the carburetor body is formed of metal so that the likelihood of having the shaft become frozen in the bore is minimized.

3. The carburetor of claim 2, further characterized by the following additional features:

(A) means to define the open and closed positions of the choke valve;

(B) a torsion spring encircling the outer end portion of the shaft and having one end connected to the carburetor body and its other end connected to the shaft to yieldingly bias the shaft in the direction to hold the choke valve open, and

(C) means on the outer end portion of the shaft by which the shaft may be turned to close the choke valve.

4. The carburetor of claim 3, further characterized by the following additional features:

(A) an air cleaner to filter the air which enters the air inlet port,

(B) and a screw to hold the air cleaner in place over the mouth of the air inlet port,

(1) said screw extending into the air inlet port and passing through a hole in the center of the choke valve, and being threaded into the carburetor body, and

(C) the choke valve having oppositely facing radial grooves in its opposite faces to receive the screw and thus allow the choke valve to assume its open position substantially parallel with the axis of the screw.

5. In a control for an internal combustion engine having an ignition system and a carburetor having a tubular body defining a mixture passage with an air inlet port, a throttle valve in the mixture passage and a choke valve to control the admission of air into the mixture passage from the air inlet port, the improvement which comprises:

(A) a shaft journalled in a bore in one side of the carburetor body having its inner end connected to the choke valve to mount and adjust the same as the shaft is turned,

(1) the outer end portion of the shaft having an arm projecting radially therefrom to provide means by which the shaft may be turned;

(B) a spring reacting between the shaft and the carburetor body .biasing the same in one direction of rotation to thereby yieldingly urge the choke valve toward its open position;

(C) a mounting plate fixed to the carburetor body at the side thereof at which said shaft is located and with the plane of the mounting plate substantially parallel to the axis of the shaft;

(D) a control lever pivoted to said plate to swing about a fixed axis perpendicular to the plate;

(B) an abutment on the control lever to collide with said arm which projects from the shaft, and thereby turn the shaft in opposition to the spring bias thereon as the lever is swung about its pivotal mounting in one direction beyond a predetermined position;

(F) means providing a connection between the con trol lever and the throttle valve through which adjustment of the lever effects adjustment of the throttle valve; and

(G) an ignition grounding switch carried by the mounting plate with a portion thereof projecting through a hole in the plate into the path of a portion of the control lever to be engaged thereby and thereby effect grounding of the ignition system upon movement of the control lever to a predetermined position at which the choke valve is open and the throttle valve closed.

No references cited.

RICHARD B. WILKINSON, Primary Examiner.

KARL J. ALBRECHT, Examiner. 

5. IN A CONTROL FOR AN INTERNAL COMBUSTION ENGINE HAVING AN IGNITION SYSTEM AND A CARBURETOR HAVING A TUBULAR BODY DEFINING A MIXTURE PASSAGE WITH AN AIR INLET PORT, A THROTTLE VALVE IN THE MIXTURE PASSAGE AND A CHOKE VALVE TO CONTROL THE ADMISSION OF AIR INTO THE MIXTURE PASSAGE FROM THE AIR INLET PORT, THE IMPROVEMENT WHICH COMPRISESD: (A) A SHAFT JOURNALLED IN A BORE IN ONE SIDE OF THE CARBURETOR BODY HAVING ITS INNER END CONNECTED TO THE CHOKE VALVE TO MOUNT AND ADJUST THE SAME AS THE SHAFT IS TURNED, (1) THE OUTER END PORTION OF THE SHAFT HAVING AN ARM PROJECTING RADIALLY THEREFROM TO PROVIDE MEANS BY WHICH THE SHAFT MAY BE TURNED; (B) A SPRING REACTING BETWEEN THE SHAFT AND THE CARBURETOR BODY BIASING THE SAME IN ONE DIRECTION ROTATION TO THEREBY YIELDING URGE THE CHOKE VALVE TOWARD ITS OPEN POSITION; (C) A MOUNTING PLATE FIXED TO THE CARBURETOR BODY AT THE SIDE THEREOF AT WHICH SAID SHAFT IS LOCATED AND WITH THE PLANE OF THE MOUNTING PLATE SUBSTANTIALLY PARALLEL TO THE AXIS OF THE SHAFT; (D) A CONTROL LEVEL PIVOTED TO SAID PLATE TO SWING ABOUT A FIXED AXIS PERPENDICULAR TO THE PLATE; (E) AN ABUTMENT ON THE CONTROL LEVER TO COLLIDE WITH SAID ARM WHICH PROJECTS FROM THE SHAFT, AND THEREBY TURN THE SHAFT IN OPPOSITION TO THE SPRING BIAS THEREON AS THE LEVER IS SWUNG ABOUT ITS PIVOTAL MOUNTING IN ONE DIRECTION BEYOND A PREDETERMINED POSITION; (F) MEANS PROVIDING A CONNECTION BETWEEN THE CONTROL LEVER AND THE THROTTLE VALVE THROUGH WHICH ADJUSTMENT OF THE LEVER EFFECTS ADJUSTMENT OF THE THROTTLE VALVE; AND (G) AN IGNITION GROUNDING SWITCH CARRIED BY THE MOUNTINH PLATE WITH A PORTION THEREOF PROJECTING THROUGH A HOLE IN THE PLATE INTO THE PATH OF A PORTION OF THE CONTROL LEVER TO BE ENGAGED THEREBY AND THEREBY EFFECT GROUNDING OF THE IGNITION SYSTEM UPON MOVEMENT OF THE CONTROL LEVER TO A PREDETERMINED POSITION AT WHICH THE CHOKE VALVE IS OPEN AND THE THROTTLE VALVE CLOSED. 